Ureteral stent for placement in a kidney and bladder

ABSTRACT

Provided is a ureteral stent (= 50 ) including a bladder portion (= 52 ) positioned in a bladder of a patient, a kidney portion (= 54 ) positioned in a kidney and ureteral passageway of the patient, and one or more tethers (= 56 ) coupling the bladder portion to the kidney portion. The ureteral stent allows urine to pass around a blockage, and allows a ureter orifice connecting the ureteral passageway to the bladder to move between a compressed state and an uncompressed state to prevent or minimize urinary reflux, flank pain, blood in the urine, etc., while allowing the bladder portion to move freely in the bladder to prevent the bladder portion from irritating the trigone muscle.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/657,228 filed Jun. 8, 2012, which is hereby incorporated herein byreference.

FIELD OF INVENTION

The present invention relates generally to implantable medical devices,and more particularly to stents, such as ureteral stents.

BACKGROUND

The urinary tract has a pair of kidneys that connect to a bladder byureteral passageways, and a urethra that extends from the bladder to theexterior of a patient. Urine is made by the kidneys, passed through theureteral passageway, stored in the bladder and ultimately voided fromthe urethra. A urinary sphincter is positioned around the urethra nearthe base of the bladder to control the flow of urine from the bladder.

The ureteral passageways normally allow urine to pass from the kidney tothe bladder by peristalsis. When the bladder fills with urine, thebladder compresses a segment of the ureteral passageway that passesthrough a wall of the bladder to prevent urine from going backwards fromthe bladder into the kidney. These passageways can become blocked bytumors or kidney stones thereby preventing normal urine flow, and theresulting high pressure within the kidneys can cause pain to thepatient. To reopen a blocked ureteral passageway, a ureteral stent canbe positioned in the patient. The stent holds the blockage in thepassageway open, for example to allow a small kidney stone to pass. Thisenables urine to flow from the kidney into the bladder, reduces kidneypressure, and reduces pain of the patient.

SUMMARY OF INVENTION

The present invention provides a ureteral stent including a bladderportion positioned in a bladder of a patient, a kidney portionpositioned in a kidney and ureteral passageway of the patient, and oneor more tethers coupling the bladder portion to the kidney portion. Theureteral stent allows urine to pass around a blockage, and allows aureter orifice connecting the ureteral passageway to the bladder to movebetween a compressed state and an uncompressed state to prevent orminimize urinary reflux, flank pain, blood in the urine, etc., whileallowing the bladder portion to move freely in the bladder to preventthe bladder portion from irritating the trigone muscle.

According to one aspect of the invention, a ureteral stent for placementin a bladder, a kidney and a ureteral passageway connecting the bladderand kidney is provided. The ureteral stent includes a bladder portionconfigured to be positioned in the bladder, the bladder portion beingresilient and biased in an unrestrained position to prevent the bladderportion from migrating into the ureteral passageway when positioned inthe bladder, a kidney portion configured to be positioned in the kidneyand the ureteral passageway, the kidney portion having a ureter portionconfigured to be positioned in the kidney and the ureteral passageway toplace the ureteral passageway in an open state and a resilient fixingportion biased in an unrestrained position to secure the resilientfixing portion in the kidney when positioned in the kidney, and at leastone tether coupled to the bladder portion and the ureter portion toallow the bladder portion to float in the bladder and to allow a ureterorifice connecting the ureteral passageway to the bladder to movebetween a compressed state and an uncompressed state.

The bladder portion and the fixing portion are movable between arestrained position when being positioned in the bladder and kidney,respectively, and the unrestrained position when positioned in thebladder and kidney, respectively.

The bladder portion and kidney portion are substantially straight whenin the restrained position and curved when in the unrestrained position.

The bladder portion and kidney portion each include at least oneradiopaque element on outer surfaces thereof to assist an operator inpositioning the stent.

The bladder portion and kidney portion have first and second ends,respectively, each end having at least one radiopaque element.

The bladder portion and ureter portion of the kidney portion eachinclude a least one opening in a wall thereof providing a passagebetween an outside of the bladder and kidney portions and an inside ofthe bladder and kidney portions for receiving the tether.

The tether extends from the inside of the bladder and kidney portions tothe outside of the bladder portions, and wherein the tether has a firstend and a second end coupled together outside the bladder and kidneyportions forming a coupled tether portion.

The ureteral stent further includes sleeve coupled to the wall of thebladder portion adjacent the opening in the wall, the sleeve coveringthe coupled tether portion.

The bladder portion includes a tip at a first end opposite a second endcoupled to the tether, the tip having a stiffness greater than astiffness of the bladder portion.

The tether is a suture.

The bladder portion, kidney portion and tether are formed from anextruded tubular member.

A section of the tubular member is removed to form the tether.

The bladder portion is a flexible loop when in the unrestrainedposition.

The bladder portion is J-shaped when in the unrestrained position.

The bladder portion is helical when in the unrestrained position.

The fixing portion is a flexible loop in the unrestrained position.

The fixing portion is J-shaped in the unrestrained position.

The fixing portion is helical when in the unrestrained position.

The bladder portion and kidney portion each Include a least one openingin a wall thereof providing a fluid passage between an outside of thebladder and kidney portions and an inside of the bladder and kidneyportions.

The kidney portion has a durometer between about 50 shore A and about 80shore A.

The resilient fixing portion has a durometer greater than a durometer ofthe ureter portion.

The bladder portion has a durometer between about 25 shore A and about50 shore A.

According to another aspect of the invention, a ureteral stent forplacement in a bladder, a kidney and a ureteral passageway connectingthe bladder and kidney for allowing urine and/or stones to flow from thekidney to the bladder and not from the bladder to the kidney isprovided. The ureteral stent includes a resilient bladder portionconfigured to be positioned in the bladder, the bladder portion beingbiased in an unrestrained position, a kidney portion having a resilientfixing portion configured to be positioned in the kidney and a ureterportion configured to be positioned in the kidney and the ureteralpassageway, the resilient fixing portion being biased in an unrestrainedposition, and one or more threads connecting the bladder portion and theureter portion.

The one or more threads is a suture.

According to still another aspect of the invention, a method for forminga ureteral stent having a bladder portion, a kidney portion, and atether extending therebetween is provided. The method includes extrudingthe stent to form a flexible tubular member, removing a section of thetubular member to form the tether, modifying the bladder portion to forma resilient fixing portion biased in an unrestrained position, andmodifying the kidney portion to form a resilient fixing portion biasedin an unrestrained position.

The foregoing and other features of the invention are hereinafterdescribed in greater detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an exemplary stent according to theinvention positioned in a patient;

FIG. 2 is a schematic view of the exemplary stent of FIG. 1;

FIG. 3 is a schematic view of another exemplary stent according to theinvention;

FIG. 4 is a schematic view of yet another exemplary stent according tothe invention;

FIG. 5 is a schematic view of still another exemplary stent according tothe invention;

FIG. 6 is a schematic view of a further exemplary stent according to theinvention;

FIG. 6A is a top view of a kidney portion of the stent of FIG. 6;

FIGS. 7 and 8 are schematic views of still a further exemplary stentaccording to the invention;

FIG. 9 is a schematic view of yet another exemplary stent according tothe invention;

FIG. 10 is a schematic view of a further exemplary stent according tothe invention; and

FIG. 11 is a schematic view of a yet further exemplary stent accordingto the invention.

DETAILED DESCRIPTION

The principles of the present application have particular application toureteral stents for unblocking a ureteral passageway and thus will bedescribed below chiefly in this context. It will, of course, beappreciated and also understood that the principles of the applicationmay be useful in other medical applications, such as other stentapplications, for example biliary stents.

Referring now in detail to the drawings and initially to FIG. 1, a pairof kidneys 10 and 12 and a bladder 14 of a patient are shown. Thekidneys 10 and 12 are connected to the bladder 14 by respective ureteralpassageways 16 and 18. The ureteral passageways 16 and 18 each include aportion extending into the bladder 14 that moves from an uncompressedstate to compressed state and in a normal state only allows urine topass from the kidneys 10 and 12 to the bladder 14 with the help ofperistalsis of the ureter. When one of the passageways 16 and 18 becomesblocked, for example by swelling near one of the kidneys 10 and 12 orblockage from a kidney or ureteral stone, a ureteral stent may bepositioned in the kidney 10, 12, ureteral passageway 16, 18 and bladder14 to assist in opening the passageway 16, 18 to aid in the flow ofurine.

The ureteral stent may be formed by a tube extending from the kidney 10,12 to the bladder 14, the tube having a first helical end positioned inthe kidney and a second helical end positioned in the bladder. Althoughsuch a stent allows urine to flow through and around the tube into thebladder, the tube may cause or contribute to patient discomfort andfurther medical problems. For example, the tube causes ureter orifices20 and 22, which normally move from a compressed state to anuncompressed state, to remain open at all times allowing urine to flowfrom the bladder 14 to the kidney 10, 12 and the kidney 10, 12 to thebladder 14. Keeping the ureter orifices 20 and 22 open, therebypreventing the orifices 20 and 22 from compressing to prevent urine fromflowing from the bladder 14 to the kidneys 10 and 12, may lead tourinary reflux and flank pain, for example. The bladder end of theureteral stent also can migrate over time such that it rests on or bangsagainst a trigone muscle 24 of the patient or wall of the bladder 14,causing blood in the urine, a continual urge to urinate, and bladderspasms resulting from stent pain and therefore increased discomfort ofthe patient.

To minimize the footprint of the stent in the bladder 14 and/or near theureteral orifices 20 and 22 and to allow urine to flow in a singledirection from the kidneys 10 and 12 to the bladder 14 and not from thebladder 14 to the kidneys 10 and 12, thereby reducing the adverseaffects associated with stents, an exemplary ureteral stent 50 isprovided. As shown in FIGS. 1 and 2, the stent 50 includes a bladderportion 52 positioned in the bladder 14, a kidney portion 54 positionedin the kidney 10 and ureteral passageway 16, and one or more tethers 56coupling the bladder portion 52 to the kidney portion 54. The tether 56may be a suitable thread, which is not limited to fibers, and mayinclude, for example, a wire, such as a thin wire. Although not shown,it will be appreciated that the stent 50 may additionally oralternatively be positioned in the kidney 12 and ureteral passageway 18.

The bladder portion 52 is a resilient fixing member having any suitableshape, such as a tube that is curved in a flexible loop as shown in FIG.2 when unrestrained to prevent the bladder portion 52 from migratinginto the ureteral passageway 16. The bladder portion 52 is in anunrestrained shape when positioned in the bladder 14, and in arestrained shape, such as a substantially straight shape, when beingpositioned in the bladder 14. It will be appreciated that the bladderportion may be any suitable shape when unrestrained, such as J-shaped(FIG. 3), helical (FIGS. 4 and 5), t-bar (FIG. 6), triangular (FIG. 9),circular (FIG. 10), etc. It will also be appreciated that the bladderportion may be made of any suitable material that does not irritate thepatient's ureter tissue, such as urethane polymer, silicone, athermoplastic, for example a thermoplastic polymer or elastomer, etc. Itwill also be appreciated that the suitable material may be a buoyantmaterial to allow the bladder portion to float in the bladder, forexample when the bladder is filled with urine, to allow the bladderportion to float off the trigone thereby decreasing irritation.

The bladder portion 52 may include one or more openings 60 in a wall ofthe bladder portion that allow fluid to flow in/out of the bladderportion. The openings may be any suitable shape and size, such as aspiral, a circular opening, etc. The bladder portion 52 may also includeat least one radiopaque element, such as a radiopaque band, and in theillustrated embodiment radiopaque bands 62 and 64 near first and secondends 66 and 68 of the bladder portion, respectively. The radiopaquebands may be any suitable radiopaque element provided to assist anoperator in placing the stent 50. Additionally or alternatively, it willbe appreciated that the bladder portion 52 may be radiopaque to assistin positioning the stent. The bladder portion may also include a tip orring 70 at the first end 66 having a stiffness greater than a stiffnessof the rest of the bladder portion 52 to assist in the positioning ofthe stent 50.

Similar to the bladder portion 52, the kidney portion 54 has a resilientfixing portion 76, such as a tube in the form of a flexible loop whenunrestrained to secure the kidney portion in the kidney 10. Theresilient fixing portion 76 is in an unrestrained shape when positionedin the kidney, and in a restrained shape, such as a substantiallystraight shape, when being positioned in the kidney. It will beappreciated that the fixing portion may be any suitable shape whenunrestrained, such as J-shaped (FIG. 3), helical (FIGS. 4 and 5), etc.It will also be appreciated that the bladder portion 52 and kidneyportion 54 may have the same or different shapes when unrestrained, forexample the bladder portion 52 and kidney portion 54 may both be aflexible loop as shown in FIG. 2, the bladder portion 52 or kidneyportion 54 may be J-shaped and the other portion may be helical, etc.

The kidney portion 54 may be made of any suitable material that does notirritate the patient's ureter tissue, such as urethane polymer,silicone, a thermoplastic, for example a thermoplastic polymer orelastomer, etc. It will be appreciated that the kidney portion andbladder portion may be made of the same or different materials havingthe same or different durometers that are sufficient to allow fordelivery reliability during placement while having tensile propertiesallowing for removal from the body. The kidney portion may have adurometer, for example, of 50 to 80 shore A and preferably 50 to 60shore A, and the bladder portion may have a durometer, for example, of25 to 50 shore A, and preferably 30 to 40 shore A. It will also beappreciated that the kidney portion, bladder portion, and/or tether maybe made of one or more of an absorbable or non-absorbable material, amaterial to prevent calcification, a material to prevent incrustation,and may additionally or alternatively be impregnated with a suitableantibiotic and/or be drug-eluting.

In an embodiment, the bladder portion 52 has a softer durometer than thekidney portion 54 so that the bladder portion 52 is compliant withbladder contractions and to reduce irritation to the trigone muscle 24.Additionally or alternatively, the resilient fixing portion 76 of thekidney portion 54 is harder than a ureter portion 78 of the kidneyportion 54. For example, the kidney portion 54 may have transition zonesalong its length going from a harder durometer at the fixing portion 76to a softer durometer at the end of the ureter portion 78. It will alsobe appreciated that the bladder portion 52 and/or kidney portion 54 maybe heat activated such that the portions are stiffer during placementand soften after placement in the body.

Referring again to the kidney portion 54, the kidney portion has theureter portion 78, which may be a flexible tubular portion, configuredto extend from the resilient fixing portion 76 in the kidney 10 into theureteral passageway 16 to keep the passageway open, for example whenthere is swelling between the kidney 10 and passageway 16. The kidneyportion 54 may also include one or more openings 80 in a wall of thekidney portion 54 that allow fluid to flow in/out of the kidney portion54. The openings may be any suitable shape and size, such as a spiral(FIG. 3), a circular opening, etc.

The kidney portion 54 also includes at least one radiopaque element,such as a radiopaque band, and in the illustrated embodiment radiopaquebands 82 and 84 near first and second ends 86 and 88 of the kidneyportion 54, respectively, although it will be appreciated that thekidney portion 54 may additionally or alternatively be radiopaque toassist in placing the stent. It will also be appreciated that thebladder portion 52 and/or kidney portion 54 may include measurementmarkers along their respective lengths to assist in positioning thestent 50.

As noted above, the bladder portion 52 and kidney portion 54 are coupledtogether by one or more tethers 56. The tethers 56 have a thin flexiblecross-section such that a transmural portion of the ureteral passageway,which passes through the bladder wall starting at the ureter opening andcontinuing through the thickness of the bladder 14, can clamp or remainin its normal state around the tethers 56. This allows for the singledirection of urine flow from the kidney 10 to the bladder 14 to bemaintained and prevents the flow or reflux of urine from the bladder 14to the kidney 10. The tethers 56 may be any suitable tether having anysuitable cross-sectional shape, such as a suitable suture made ofcotton, a polymer such as nylon, etc. The tethers may also be anysuitable length. For example, the tethers may be uniform in length forpatients of varying sizes and the ureter portion 78 may be altered inlength to accommodate patients of varying sizes and/or the suturelengths may be varied for patients of varying sizes. It will also beappreciated that the one or more tethers 56 may include one or moreradiopaque marks along their lengths.

The tethers 56 are coupled to the second end 68 of the bladder portionand the second end 88 of the kidney portion in any suitable manner, forexample by adhesive, knotting, etc. For example, as shown in FIG. 2, thetether 56 has an end received in an opening 92 at the second end 88 ofthe kidney portion 54 such that a portion of the tether 56 is outsidethe kidney portion 54 and a portion is inside the kidney portion 54. Theportion of the tether 56 inside the kidney portion 54 extends to anInside of the bladder portion 52, where the tether extends out of anopening 72 in the bladder portion 52. Ends of the tether 56 are coupledtogether outside the bladder portion or the kidney portion, for exampleby tying the two ends together forming a knot. The excess tether createdby the tying may then be cut off.

In an embodiment, a sleeve 74, such as a heat shrink, tape, UV adhesive,etc., is coupled to the second end 68 of the bladder portion to holddown the knot and excess tether to prevent or minimize irritation to thepatient. It will be appreciated that by using the sleeve 74, the excesstether can be left longer than without the use of a sleeve 74 allowingthe tether to lie down, reducing the thickness of the bladder portion52. It will also be appreciated that the sleeve 74 may have radiopaquematerial on an external surface thereof to either replace the radiopaqueband 64 or be used in conjunction with the band. Alternatively, theradiopaque band 64 may be positioned over the sleeve 74 or knot. Thesleeve 74 is provided on the kidney portion 54 and/or the bladderportion 52 to cover knots on the outside of the kidney and/or bladderportion. It will be appreciated, however, that a stent may be providedhaving knots on the inside of the bladder portion and/or the kidneyportion, in which case the sleeve may be omitted.

When the stent 50 is positioned in the body of the patient, the one ormore tethers 56 extend from the ureteral passageway 16, through theureter orifice 20 and into the bladder 14. The one or more tethers 56allow the bladder portion 52 to anchor the kidney portion 54 to keep theureter portion 78 in position in the ureteral passageway 16, for exampleto prevent the ureter portion 78 from curling up. The tether also allowsthe ureter orifice 20 to freely move between the compressed state andthe uncompressed state to allow the ureter orifice to move to thecompressed state when the bladder fills, thereby preventing urine frommoving backwards. The tether also allows urine to pass in Its normaldirection from the kidney to the bladder. In this way, the tetherprevents or minimizes urinary reflux, flank pain, patient discomfort,etc.

The one or more tethers 56 additionally allow the bladder portion 52 tomove freely in the bladder 14, for example as the bladder fills withurine, to prevent the bladder portion 54 from Irritating the trigonemuscle; to prevent or minimize bladder spasms, blood in the urine and aconstant urge to urinate; and to avoid a rigid positioning of the stentthat would hold the stent in one position over the trigone. The bladderportion thereby freely floats and/or dangles within the bladder, i.e.not held in a rigid position, and is constrained only by the length ofthe tether.

When being positioned, the kidney portion 54 and the bladder portion 52are restrained, i.e. substantially straightened, to allow the portionsto be navigated through the patient. It should be appreciated that forpurposes of positioning, at least the ureter portion 78 of the kidneyportion 54 has an inner diameter that is less than an inner diameter ofthe bladder portion 52. Once the kidney portion 54 is positioned and aguidewire withdrawn, the kidney portion moves to its unrestrained shapewhere the resilient fixing portion 76 is secured in the kidney 10 andthe ureter portion 78 extends from the kidney 10 into the ureteralpassageway 16 to keep the passageway open near the kidney. Similarly,once the bladder portion 52 is positioned and the guidewire withdrawn,the bladder portion 52 moves to its unrestrained shape where the bladderportion 52 anchors the ureter portion 78 while allowing the ureterorifice 20 to freely move between the compressed state and uncompressedstate.

Turning now to FIGS. 3-10, exemplary embodiments of the ureteral stentis shown at 150, 250, 350, 450, 550, 650, 750 and 850. The ureteralstents 150, 250, 350, 450, 550, 650, 750 and 850 are substantially thesame as the above-referenced ureteral stent 50, and consequently thesame reference numerals but indexed by 100, 200, 300, 400, 500, 600, 700and 800 respectively are used to denote structures corresponding tosimilar structures in the stents. In addition, the foregoing descriptionof the stent 50 is equally applicable to the stent 150, 250, 350, 450,550, 650, 750 and 850 except as noted below. Moreover, it will beappreciated upon reading and understanding the specification thataspects of the stents may be substituted for one another or used inconjunction with one another where applicable.

Referring now to FIG. 3, the bladder portion 152 is a J-shaped flexibletube when unrestrained that prevents the bladder portion 152 frommigrating into the ureteral passageway 16. Similarly, the fixing portion176 of the kidney portion 154 is a J-shaped flexible tube whenunrestrained to secure the kidney portion in the kidney 10. The secondend 168 of the bladder portion 152 and the second end 188 of the kidneyportion 154 are each coupled to a tether 156 in any suitable manner. Thekidney portion 154 includes one or more spiral openings 180 extendingthrough the wall of the kidney portion and the bladder portion 152includes one or more circular openings 160 extending through the wall ofthe bladder portion to allow fluid to flow in/out of the kidney portion154 and bladder portion 152. It will be appreciated that the bladderportion 152 may additionally or alternatively include one or more spiralopenings extending through the wall of the bladder portion and thekidney portion 154 may additionally or alternatively include one or morecircular openings extending through the wall of the kidney portion.

The kidney portion 154 has a diameter near the first end 186 that islarger than the diameter at the second end 188. For example, thediameter of the kidney portion may gradually taper down from the firstend 186 to the second end 188. It will also be appreciated that thebladder portion 154 may have a diameter at the second end 168 that islarger than the diameter at the first end 166 of the bladder portion152. Additionally, the diameter at the second end 168 of the bladderportion 152 may be substantially equal to or less than the diameter ofthe kidney portion at the second end 188, and the diameter at the firstend 166 less than the diameter at the second end 168. Such a stent maybe used as an endopyelotomy stent, providing a large diameter near thekidney for ureteral healing and a smaller diameter in the bladder forpatient comfort.

Referring now to FIGS. 4 and 5, the bladder portions 252 and 352 arehelical flexible tubes when unrestrained that prevent the bladderportions 252 and 352 from migrating into the ureteral passageway.Similarly, the fixing portions 276 and 376 of the kidney portions 254and 354 are helical flexible tubes when unrestrained to secure thekidney portions in the kidney. The helical flexible tube portions 252,352, 276, 376 of the bladder portions 252 and 352 and kidney portions254 and 354 may have any suitable number of coils. The second ends 268and 368 of the bladder portions 252 and 352 and the second ends 288 and388 of the kidney portions 254 and 354 are each coupled to a respectivetether 256, 356 in any suitable manner, such as by an adhesive that iscovered by a sleeve.

The ureter portions 278 and 378 of the kidney portions 254 and 354 havevarying lengths for use with patients having ureteral passageways ofvarying sizes, such as pediatric lengths and sizes, adult lengths andsizes, etc. As shown, the ureter portion 278 has a length L1 for usewith a patient having a ureteral passageway of a first length, and theureter portion 378 has a length L2, which is greater than the length L1,for use with a patient having a ureteral passageway of a second lengthgreater than the first length. Additionally, the bladder portion 252includes a substantially straightened portion 290 that is coupled to thetether, while the bladder portion 352 is formed without a straightenedportion. It will be appreciated that the substantially straightenedportion 290 may be included in the bladder portion 352 and not includedin the bladder portion 252.

Referring now to FIG. 6, the bladder portion 452 is a t-bar thatprevents the bladder portion 452 from migrating into the ureteralpassageway. The kidney portion 454 is shown as a J-shaped flexible tube,although it will be appreciated the kidney portion may have any suitableshape as discussed above. Ends of a tubular portion 467 of the t-bar andthe second end 488 of the kidney portion 454 are coupled to two suitabletethers in any suitable manner, for example, by knots on the outside ofthe t-bar and/or ureter portion 478 that are covered by a sleeve asdiscussed above or by knots on an inside of the ends of the tubularportion 467 and/or ureter portion 478.

The bladder portion 452 and/or kidney portion 454 may include one ormore channels 480 along the length thereof that are provided to guidefluid, such as urine, out of the kidney 10 and into the bladder 14. Forexample, FIG. 6A shows a top view of the kidney portion 454 includingthree channels 480 that are circumferentially spaced around the kidneyportion 454. The channels 480 may be evenly circumferentially spacedaround the kidney portion 454 or spaced in any other suitable manner.

Referring now to FIGS. 7 and 8, the stent 550 is formed by extruding thestent to form a flexible tubular member 600. Then at region 602, asection of the tubular member 600 is removed to form the tether 556.Before or after removing the section at region 602, geometricmodifications, such as forming the fixing elements 552 and 554, addingretention notches, openings, etc. may be performed, for example byheat-forming, and surface edge softening may be performed.

Referring now to FIG. 9, the kidney portion 654 is a J-shaped flexibletube when unrestrained that secures the kidney portion 654 in the kidney10. The bladder portion 652 is substantially triangular whenunrestrained to prevent the bladder portion 652 from migrating into theureteral passageway 16. The second end 668 of the bladder portion 652and the second end 688 of the kidney portion 654 are each coupled to atether 656 in any suitable manner. During positioning, the substantiallytriangular bladder portion is substantially straightened.

Referring now to FIG. 10, the kidney portion 754 is a J-shaped flexibletube when unrestrained that secures the kidney portion 754 in the kidney10. The bladder portion 752 is substantially circular and sized to belarger than the ureter orifice 20 to prevent the bladder portion 752from migrating into the ureteral passageway 16. The bladder portion 752includes a through-hole 767 extending therethrough and one or moreopenings 760 extending through the bladder portion. The bladder portionmay also include a seat at one end of the through-hole 767 for an end ofa pusher to seat against during placement.

Referring now to FIG. 11, the kidney portion 854 is a J-shaped flexibletube when unrestrained that secures the kidney portion 854 in the kidney10. Similarly, the bladder portion 852 is a J-shaped flexible tube whenunrestrained that prevents the bladder portion 852 from migrating intothe ureteral passageway 16. The bladder portion 852 includes a firstlumen 853 for the knot 857 to be disposed to prevent the knot fromirritating the trigone area, for example, and a second lumen 855 forreceiving a stent pusher assembly and guidewire. One or more openings860 may be provided in the first and/or second lumens that allow fluidto flow in/out of the bladder portion. Similarly, the kidney portion mayinclude a first lumen for a knot to be disposed and a second lumen forreceiving a guidewire.

The above-described ureteral stents may be positioned in the kidney 10and bladder 14 using any suitable stent pusher assembly, such as thetype disclosed in U.S. Patent Application No. 61/657,238, which ishereby incorporated herein by reference.

Although the invention has been shown and described with respect to acertain embodiment or embodiments, it is obvious that equivalentalterations and modifications will occur to others skilled in the artupon the reading and understanding of this specification and the annexeddrawings. In particular regard to the various functions performed by theabove described elements (components, assemblies, devices, compositions,etc.), the terms (including a 30 o reference to a “means”) used todescribe such elements are intended to correspond, unless otherwiseindicated, to any element which performs the specified function of thedescribed element (i.e., that is functionally equivalent), even thoughnot structurally equivalent to the disclosed structure which performsthe function in the herein illustrated exemplary embodiment orembodiments of the invention. In addition, while a particular feature ofthe invention may have been described above with respect to only one ormore of several illustrated embodiments, such feature may be combinedwith one or more other features of the other embodiments, as may bedesired and advantageous for any given or particular application.

1-25. (canceled)
 26. A ureteral stent for placement in a bladder, akidney and a ureteral passageway connecting the bladder and kidney, theureteral stent including: a bladder portion configured to be positionedin the bladder, the bladder portion being resilient and biased in anunrestrained position to prevent the bladder portion from migrating intothe ureteral passageway when positioned in the bladder; a kidney portionhaving first and second ends and being configured to be positioned inthe kidney and the ureteral passageway, the kidney portion having aureter portion configured to be positioned in the kidney and theureteral passageway to place the ureteral passageway in an open stateand a resilient fixing portion biased in an unrestrained position tosecure the resilient fixing portion in the kidney when positioned in thekidney, wherein the ureter portion includes an opening in a wall of theureter portion near the second end; and a tether having a portionextending through the opening in the ureter portion, wherein the tethercouples the bladder portion and the ureter portion to allow the bladderportion to float in the bladder and to allow a ureter orifice connectingthe ureteral passageway to the bladder to move between a compressedstate and an uncompressed state.
 27. The ureteral stent according toclaim 26, further including a sleeve coupled to the wall of the ureterportion adjacent the opening in the wall, the sleeve covering theopening.
 28. The ureteral stent according to claim 26, wherein thetether is coupled to the bladder portion by an adhesive.
 29. Theureteral stent according to claim 26, wherein the bladder portion andkidney portion each include at least one radiopaque element on outersurfaces thereof to assist an operator in positioning the stent.
 30. Theureteral stent according to claim 29, wherein the bladder portion andkidney portion have first and second ends, respectively, each end havingat least one radiopaque element.
 31. The ureteral stent according toclaim 26, wherein the bladder portion includes a tip at a first endopposite a second end coupled to the at least one tether, the tip havinga stiffness greater than a stiffness of a remaining portion of thebladder portion.
 32. The ureteral stent according to claim 26, whereinthe bladder portion includes a through-hole extending therethrough and aseat at one end of the through-hole.
 33. The ureteral stent according toclaim 26, wherein the bladder portion and the fixing portion are movablebetween respective restrained positions when being positioned in thebladder and kidney, respectively, and the respective unrestrainedpositions when positioned in the bladder and kidney, respectively. 34.The ureteral stent according to claim 33, wherein the bladder portionand kidney portion are substantially straight when in the respectiverestrained positions and curved when in the respective unrestrainedpositions.
 35. The ureteral stent according to claim 26, wherein thebladder portion is triangular when in its unrestrained position.
 36. Theureteral stent according to claim 26, wherein the resilient fixingportion has a durometer greater than a durometer of the ureter portion.37. The ureteral stent according to claim 26, wherein the bladderportion and kidney portion each include at least one opening in a wallthereof providing a fluid passage between an outside of the bladder andkidney portions and an inside of the bladder and kidney portions. 38.The ureteral stent according to claim 26, wherein the kidney portion hastransition zones along its length going from a harder durometer at thefirst end to a softer durometer at the second end.
 39. The ureteralstent according to claim 26, wherein the tether is a single tether withfirst and second ends coupled together.
 40. The ureteral stent accordingto claim 26, further including a sleeve coupled to the wall of theureter portion, the sleeve covering a portion of the tether.
 41. Aureteral stent for placement in a bladder, a kidney and a ureteralpassageway connecting the bladder and kidney for allowing urine and/orstones to flow from the kidney to the bladder and not from the bladderto the kidney, the ureteral stent including: a resilient bladder portionconfigured to be positioned in the bladder and including one or moreopenings in a wall thereof providing a fluid passage; a tubular kidneyportion defining a tubular resilient fixing portion configured to bepositioned in the kidney and a tubular ureter portion extending from theresilient fixing portion and configured to be positioned in the kidneyand the ureteral passageway to keep the passageway in an open statewhile in position, the tubular kidney portion including one or moreopenings in a wall thereof providing a fluid passage; and a tetherconnecting the bladder portion and the ureter portion.
 42. The ureteralstent according to claim 41, wherein the tether is a single tether withfirst and second ends coupled together.
 43. The ureteral stent accordingto claim 41, further including a sleeve coupled to the wall of theureter portion, the sleeve covering a portion of the tether.
 44. Theureteral stent according to claim 41, wherein the ureter portionincludes an opening, and further including a sleeve coupled to the wallof the ureter portion covering the opening.
 45. A ureteral stent forplacement in a bladder, a kidney and a ureteral passageway connectingthe bladder and kidney, the ureteral stent including: a bladder portionconfigured to be positioned in the bladder, the bladder portion beingresilient and biased in an unrestrained position to prevent the bladderportion from migrating into the ureteral passageway when positioned inthe bladder; a kidney portion configured to be positioned in the kidneyand the ureteral passageway, the kidney portion having a ureter portionconfigured to be positioned in the kidney and the ureteral passageway toplace the ureteral passageway in an open state and a resilient fixingportion biased in an unrestrained position to secure the resilientfixing portion in the kidney when positioned in the kidney; and a tethercoupled to the bladder portion and the ureter portion to allow thebladder portion to float in the bladder and to allow a ureter orificeconnecting the ureteral passageway to the bladder to move between acompressed state and an uncompressed state.